Allison Transmission Issue

Junior Member

Sporadically, when our coach hits a major bump or expansion joint, it momentarially shifts into neutral and then back into gear,. The speedometer pegs as does the tach and several warning lights come on. At the same time, the odometer stops working! This might occur once every 50-100 miles depending upon the smoothness of the highway.

I pulled the Medallion instrument cluster and added another ground in case there was a bad ground somewhere in the module. That had no effect. A local dealer's technician had a go at it but was unable to find the problem.

Has anyone out there had a similar issue, and if so, what did you do to address it?